Slot antenna with flare

ABSTRACT

A slot antenna with a flare having flare member having integrally formed therewith a first half section of antenna member and a second half section of antenna member having formed therein slots, in which the second half section of antenna member is mechanically assembled with the first half section of antenna member to provide a slot antenna member.

United States Patent Terakawa et al.

[ Jan. 14,1975

SLOT ANTENNA WITH FLARE Inventors: Takashige Terakawa,

Kanagawa-ken; Sadahiko Hidaka, Tokyo, both of Japan Kabushikikaisha Tokyo Keiki, Tokyo, Japan Filed: Aug. 15, 1973 Appl. No.: 388,425

Assignee:

Foreign Application Priority Data Aug. 18, 1972 Japan 47-96601 US. Cl. 343/771, 343/786 Int. Cl. HOlq 13/10 Field of Search 343/770, 771, 786

References Cited UNITED STATES PATENTS Katchky et a1 343/771 FOREIGN PATENTS OR APPLICATIONS 830,754 3/1960 Great Britain 343/771 Primary ExaminerEli Lieberman Attorney, Agent, or FirmMarsha11 & Yeasting [57] ABSTRACT A slot antenna with a flare having flare member having integrally formed therewith a first half section of antenna member and a second half section of antenna member having formed therein slots, in which the second half section of antenna member is mechanically assembled with the first half section of antenna member to provide a slot antenna member.

1 Claim, 6 Drawing Figures PAIENIEM 3 860,933

SHEET 1 UF 2 PRIOR ART F|G.1 B

PATENTED JAN] 4|975 sum EM 2 SLOT ANTENNA WITH FLARE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a slot antenna with a flare.

2. Description of the Prior Art A conventional type of a slot antenna with a flare has a construction that a slot antenna member previously prepared has mechanically connected thereto a flare member also previously prepared. The flare member is composed of a pair of plate portions and an angled portion extending between their side margins and is made by folding a sheet of plate. The slot antenna member is obtained by forming many slots in one shorter side wall of a waveguide of a rectangular cross-section in its lengthwise direction. The formation of the slots in the shorter side wall of the waveguide is achieved by means of milling. In this case, the waveguide is warped, bent or curved in the shape of an arc with the shorter side wall to be milled being on the inside. Therefore, it is difficult to mill the shorter side wall so that the slots may be formed to the same depth, viewed from the longitudinal direction of the wall. If the slots are formed to different depths, the antenna is poor in phase characteristics and has many unnecessary side lobes in di rectional pattern.

SUMMARY OF THE INVENTION Accordingly, this invention is to provide a slot antenna with a flare which can easily be processed and produced without providing poor phase characteristics and unnecessary side lobes.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a partial, schematic perspective view showing the construction of a conventional slot antenna with a flare;

FIGS. 13 and 1C are schematic perspective views illustrating a slot antenna member and a flare member making up the slot antenna depicted in FIG. 1A;

FIG. 2A is a partial, schematic perspective view showing the construction of a slot antenna with a flare according to this invention;

FIG. 2B is a schematic perspective view showing a half section of an antenna member making up one half section of the slot antenna member of FIG. 2A; and

FIG. 2C is a schematic perspective view illustrating a flare member having the other half section of the antenna member which is connected with the half section of the antenna member of FIG. 28 to make up the slot antenna shown in FIG. 2A.

DESCRIPTION OF THE PREFERRED EMBODIMENTS To facilitate a better understanding of this invention, a description will be given first of a conventional slot antenna with a flare with reference to FIGS. 1A to IC. As shown in FIG. 1A, the conventional slot antenna with a flare comprises a slot antenna member 3 such as shown in FIG. 18, which has slots 2 formed in one wall of the shorter side of a waveguide 1 of a rectangular cross section, and a flare member 6 such as depicted in FIG. 1C which is composed of a pair of plate portions 4a and 4b interconnected at their bases through a coupling portion 5 ofa U-shaped cross section. The slot antenna member 3 and the flare member 6 are mechanically assembled together, for example, by means of soldering, with the wall of the waveguide I of the slot antenna member 3 having no slots formed being snugly fitted in the coupling portion 5. The slots 2 of the slot antenna member 3 are usually formed by the milling process of the waveguide I. In this case, however, the processing encounters a difficulty in that since the slots 2 are formed only in one shorter side wall of the waveguide I, the waveguide I is warped, bent or curved in an arc shape as a whole, with the wall to be processed being on the inside, and consequently it is relatively difficult to form the slots 2 to the same depth in the lengthwise direction of the waveguide 1. An error that the slots 2 are formed to different depths results in poor phase characteristics of the finished slot antenna and causes many unnecessary side lobes in its directional pattern.

On the other hand, a slot antenna with a flare according to this invention has such a construction as will be apparent from the following detailed description of one example thereof shown in FIGS. 2A to 2C.

In FIG. 2, parts corresponding to those in FIG. 1 are identified by the same reference numerals and no detailed description will be repeated. As illustrated in FIG. 2A, the slot antenna according to this invention comprises one half section of an antenna member 12 such as shown in FIG. 2B which has slots 2, and a flare member 6 such as depicted in FIG. 2C which has formed integrally therewith the other section of antenna member 13. The half section of antenna member 12, having formed therein slots, corresponds to that part having the slots 2 which is obtained by dividing the waveguide of rectangular cross section shown in FIG. 1B into two along a plane parallel with the walls of the shorter side of the waveguide 1. On the other hand, the other half section of antenna member 13 corresponds to that part without the slots 2 which is obtained by dividing the waveguide l of the antenna member 3 shown in FIG. 1B in the manner described above. In practice, it is preferred that the abovementioned plane be parallel with the walls of the shorter side of the waveguide l in a plane passing through the center of the walls of the longer'side of the waveguide l in its widthwise direction. The reason therefor is that when the slot antenna member 3 depicted in FIG. 1B is excited by electromagnetic waves of TE Mode, a wall current flowing in each of the walls of the longer side of the waveguide is zero at the center of each wall of the longer side in its widthwise direction. The half section of antenna member 13 of the flare member 6' is mechanically assembled with the other half section of antenna member 12 to provide a slot antenna member 3' similar to that 3 depicted in FIG. 1A.

With such a slot antenna of this invention, the antenna member 3' is formed by assembling the half section of antenna member 1-2 having the slots 2 and the other half section of antenna member 13 formed as a unitary structure with the flare member 6. Further, the half section of antenna member 12 having the slots 2 can be obtained at a stroke by means of punching instead of milling process employed in the prior art, so that no difficulty is encountered in the formation of the slots 2 of the antenna member 3 with accuracy. Therefore, the slot antenna of this invention can easily be obtained with excellent characteristics which neither provides poor phase characteristics nor causes many unnecessary side lobes.

The foregoing description has been made in connection with the case where the flare member 6 is entirely made of a conductive material but it is also possible to make the flare member of a synthetic resin and form a conductive layer on the surface of an area of the member which will serve as the half section of antenna member 13 or over the entire area of the surface of the member. Further, in some cases, it is also possible to make the half section of antenna member 12 and form a conductive layer all over its surface. This leads to the reduction of the overall weight and cost of the antenna in addition to the effects described previously.

It will be apparent that many modifications and variations may be effected without departing from the scope of the novel concepts of this invention.

We claim as our invention:

1. A slot antenna with a flare comprising a flare memher having a first half section of antenna member formed as a unitary structure therewith, and a second half section of antenna member having formed therein slots, the first and second half sections of antenna member corresponding to that part having no slots and that part having the slots, respectively, which are obtained by dividing a slot antenna member having the slots in one of the walls of the shorter side of a waveguide of rectangular cross-section into two along a plane parallel with the walls of the shorter side of the waveguide and passing through the center of the walls of the longer side of the waveguide, and the second half section of antenna member being mechanically assembled with the first half section of antenna member formed integrally with the flare member to provide the complete slot antenna member. 

1. A slot antenna with a flare comprising a flare member having a first half section of antenna member formed as a unitary structure therewith, and a second half section of antenna member having formed therein slots, the first and second half sections of antenna member corresponding to that part having no slots and that part having the slots, respectively, which are obtained by dividing a slot antenna member having the slots in one of the walls of the shorter side of a waveguide of rectangular crosssection into two along a plane parallel with the walls of the shorter side of the waveguide and passing through the center of the walls of the longer side of the waveguide, and the second half section of antenna member being mechanically assembled with the first half section of antenna member formed integrally with the flare member to provide the complete slot antenna member. 